1. Field of the Invention
The present invention relates to a video projector which projects images on an external screen.
2. Description of the Related Art
Conventionally, a video projector, which projects images on an external screen on the basis of image signals outputted from a personal computer, for example, has a function to vary a magnification ratio to enlarge images depending on a size of a screen or a distance from the video projector to the screen. As for a relatively inexpensive video projector, for example, a user can change the magnification ratio to enlarge images by turning a zoom ring located around a projection lens which projects images.
In the relatively inexpensive video projector described above, the user should operate the zoom ring around the projection lens to vary the size of the images projected on the screen even when the video projector is in use. In operating the zoom ring, the user often blocks the image projected on the screen in front of the projection lens unintentionally, and thus, it is so inconvenient as to make the other user who watches the image feel discomfort. Such a problem can be solved by using a video projector in which an image zooming can remotely be operated, for example. It, however, is too expensive to apply such a configuration to the inexpensive video projector with simple configuration.
A conventional video projector described in, for example, Japanese Laid-Open Patent Publication No. 2005-333460 comprises movable wheels which are driven by a motor so as to adjust a location of a projected image by controlling and changing a location and an attitude of a projector body. However, the conventional video projector described in 2005-333460 has a complex configuration to drive the movable wheels, and thereby, it causes expensiveness. Thus, such a configuration of movable wheels cannot be applied to the relatively inexpensive video projector, and the above problem cannot be solved.
Another conventional video projector described in, for example, Japanese Laid-Open Patent Publication No. 2004-29356 is configured to vary a size of an image projected on a screen by moving a projector body forward and backward. However, during use of the video projector, an installation location can often be changed little, and in such a situation, the image cannot be adjusted to be an intended size without varying a magnification ratio of the projection lens. Moreover, depending on a purpose of use of the video projector, the size of the image projected on the screen is not often wished to be changed when the installation location of the video projector is changed. In this case, as for the conventional video projector described in 2004-29356, the user should operate the zoom ring, so that the above problem is not still be solved.